1. Technical Field
This disclosure relates to communication systems and, more particularly, to wireless mobile communication systems which utilize a packet data serving node (PDSN) and an authentication, authorization, and accounting (AAA) server.
2. Description of Related Art
Wireless communication systems may enable one or more mobile stations to communicate with various services through one or more packet-based networks, such as the internet. To facilitate these communications, a packet data serving node (PDSN) may be configured to function as a gateway between one or more of the wireless mobile stations and one or more of the packet-based networks.
The PDSN may seek to authenticate a wireless mobile station, to verify its authorization to communicate over the packet-based network, and/or to account for that communication. A server commonly known as an authentication, authorization, and accounting (AAA) server may be used by the PDSN to facilitate these functions. The PDSN may send requests to the AAA server seeking authentication, authorization, and/or accounting services, and the AAA server may send responses back to the PDSN.
A PDSN may need to process thousands of communications with an AAA server each second. To facilitate this throughput, the PDSN may delegate the responsibility for managing small groups of these communications to a subsystem commonly known as an AAA manager (referred to herein as a “sub-AAA manager”). A single PDSN may have over one hundred such sub-AAA managers which may all operate at approximately the same time. A single AAA server, in turn, may be shared among numerous PDSNs. Thus, a single AAA server may receive tens of thousands of requests for authentication, authorization, and/or accountings services each second.
Problems may arise with the AAA server and/or the communication system between the AAA server and the PDSN. Such problems may cause the sub-AAA manager not to receive a response to a request to an AAA server in a timely manner. If a response is not received by a sub-AAA manager within a pre-determined time, the sub-AAA manager may resend the request to the AAA server. If a response is repeatedly not received by the sub-AAA manager within the pre-determined time, the sub-AAA manager may redirect future requests to a secondary AAA server.
Delays encountered by one sub-AAA manager may be encountered by all of the AAA managers at about the same time. Thus, when an unacceptable delay occurs in connection with a request being sent by one sub-AAA manager, all of the sub-AAA managers may incur the same unacceptable delay. In turn, this may cause all of the sub-AAA managers to resend their requests. This may cause the AAA server to be even further overloaded. This may further slow the responses from the AAA server, causing even more requests to be resent. The AAA server may very quickly become overloaded with more requests than it can handle. This may seriously degrade the performance of the AAA server and may cause it to shut down.